Although the association between evangelical Protestant and Republican affiliations is now a fundamental aspect of American politics, this was not the case as recently as the early 1980s. Following work on secular political realignment and the issue evolution model of partisan change, I use four decades of repeated cross-sectional survey data to examine the dynamic correlates of evangelical Protestant and Republican affiliations, and how these factors promote changes in partisanship. Results show that evangelical Protestants have become relatively more likely to attend religious services and to oppose homosexuality, abortion, and welfare spending. Period-specific mediation models show that opposition to abortion, homosexuality, and welfare spending have become more robust predictors of Republican affiliation. By the twenty-first century, differences in Republican affiliation between evangelical Protestants and other religious affiliates are fully mediated by views of homosexuality, abortion, and welfare spending; and differences in Republican affiliation between evangelicals and the religiously unaffiliated are substantially mediated by views of homosexuality, abortion, welfare spending, and military spending. These